There are 3 characters that cannot be obtained from Character Event Wishes and Weapon Event Wishes. Aside from their initial acquisitions in The Outlander Who Caught the Wind , they can only be obtained from the Standard Wish Wanderlust Invocation , Paimon's Bargains , or Chronicled Wish :

Yes, you can get many characters as a f2p, but you have to do your daily activities, do the events, and explore a lot for chests. You won't have enough for every 5* character you might want, but you can plan ahead to get the ones you want the most. And you'll also get a lot of 4* characters by wishing in all banners.

As Genshin Impact takes place in a fantasy world, there are many non-human characters. These add a little bit of special flare to the list of nations that make up Hoyoverse's world.

Most DPS characters requires high investment especially 4* DPS because they have lower stats than 5* DPS and a lot of 5* DPS adds Crit stats per ascension. The 5* that I feel need high investment is Diluc because honestly his performance is just so-so without a full crimson set.

Rhinedottir, also known as "Gold" and by her codename “R,” is a researcher and one of the Five Sinners of Khaenri'ah. She is a practitioner of the Art of Khemia and is best known for her masterpieces, Durin and Albedo.